Travel and Transportation Many of the highways in Pennsylvania are paved with concrete rather…
Travel and Transportation Many of the highways in Pennsylvania are paved with concrete rather than tar. Suppose an experiment was conducted to determine whether the compression strength in cured concrete pavement (y, psi) is affected by the water-to-cement ratio (x1), the sand-to-cement ratio (x2), the percentage of fly ash (x3), and/or the ambient temperature during curing (x4, °F).
a. Estimate the regression coefficients in the model
Use the sign of each estimated regression coefficient to explain the effect of each predictor variable on the compression strength of concrete.
b. Construct an ANOVA table and conduct a model utility test. Use technology to find the p value associated with this test.
c. Conduct the appropriate hypothesis tests to determine the significant predictor variables.
d. Construct a normal probability plot of the residuals and the plots of the residuals versus each predictor variable. Is there any evidence of a violation in the multiple linear regression assumptions?